The present invention relates to a torque transmitting mechanism for members adapted for a longitudinal movement relative to one another.
The invention relates particularly to a torque transmitting bearing assembly incorporating a shaft supported for axial sliding movement relative to a housing by means of a roller bearing wherein the roller bearing is provided with at least one bearing race plate which is mounted for radial adjustment by means of a corresponding row of balls against a bearing race groove running axially in the shaft and which can be fixed to the housing. The bearing race plate has axially running sharp edge segments which penetrate the bore surface of the housing when the bearing is pressed in place. By this process the bearing race plate may be aligned accurately with the bearing race of the shaft.
Bearing applications of this type are previously known from German Preliminary Application No. 2,849,758. In accordance with the assembly shown in this publication, a convex conical or truncated conical surface is machined in the bearing race plate and a complementary but concave constructed conical or truncated conical surface is arranged on the front side of a housing screw. By adjusting the bearing race plate by means of the housing screw, the bearing race plate is fixed axially and in a peripheral direction by means of the coacting conical surfaces. By this arrangement, the assembly is capable of transmitting torque. The mating conical surfaces, however, produce a predetermined form fit contact and thus, if there is a slight variation in the finishing tolerances, a tilting or offset of the bearing race plate can be anticipated especially when the housing screw is not aligned with the center line of the bearing race plate or with the bearing race groove or the shaft. This offset alignment may produce undesirable play or poor running properties and result in premature failure. These defects are particularly disadvantageous when two bearing race plates are to be used in the assembly for the transmission of torque. In these instances, a uniform distribution of the torque to both bearing race plates is only seldom possible since in the case of plural plates all individual parts must be produced and installed without any tolerance leeway. In practice this is, however, not feasible. Furthermore, the housing must be of a substantial wall thickness in order to machine threads for the housing screw. Additionally, the housing screw must be easily accessible from the outside in order to make any adjustments at all and in some applications, the space requirements do not allow this. In summary, these prior arrangements are not expedient since threads and corresponding housing screws must always be provided in the housing.
With the foregoing in mind, it is an object of the present invention to provide a simple and inexpensive means for adjusting and fixing the torque transmitting bearing race plate in a torque transmitting bearing assembly of the above type without the need for special provisions in the housing. To this end, the outer periphery of the radially adjustable bearing race plate confronting the bore surface of the housing is provided with sharp projections in the form of a knife edge or the like which when inserted into the bore penetrates the bore surface. The knife edges preferably extend in a longitudinal direction so that the parts may be assembled by a telescoping assembly action.
The knife-like edges of the race plate projections are of a predetermined suitable height so that they project only slightly radially over the outside surface of the entire roller bearing for longitudinal movements. During installation, the roller bearing with the shaft is only pressed into the bore of the housing provided for this purpose. The sharp knife-like edges of the race plate penetrate the bore surface whereby pressure is applied through the row of balls on the bearing race groove of the shaft and consequently the bearing race plate is automatically aligned into its ideal operating position. After having been pressed in place in this fashion, the bearing race plate is fixed radially and in a peripheral direction and is capable of transmitting torque in both directions. Since the bearing race plate conforms closely and uniformly to the row of rolling elements for example, balls, which in turn conform to the bearing race of the shaft as the result of the radial force produced when being pressed into the bore, the bearing race plate cannot be tilted and offset. Two torque transmitting bearing race plates may be utilized which provide special advantages. For example, as the result of the automatic no-play alignment of the bearing race plates during assembly of the roller bearing, a uniform distribution of the torque on both bearing race plates is also obtained. Further, because of the shape and dimensions of the knife-like edges, the level of pretension of the appropriate rows of balls can be determined. Further, if only a slight pretension or no pretension or preloading is desired, assembling shafts may be used optionally, the bearing race depth of which are somewhat less than in the shaft to be used later.
In accordance with the present invention, the wall thickness of the housing may also be made very small or narrow since neither a thread nor any devices for fixing the torque transmitting bearing race plate is required. Additionally, it is not necessary to provide any adjustment means from outside of the housing so that this space which is required in some prior assemblies can be used for other more useful purposes. This is especially significant when the assembly is located in a difficult to reach place or when the housing mounts other drive mechanisms such as gears, couplings or the like. A further advantage is that the user of roller bearings for longitudinal movement applications does not need to provide anything in the housing except the bore. This is especially important since many errors may be made particularly during assembly which severely affect the running properties of the unit.
In accordance with another feature of the present invention, the knife-like projections on the bearing race plate may be formed as a plurality of discrete interrupted sections in the longitudinal direction, each section being of progressively greater radial height from one end of the race plate to the other end. During assembly of the roller bearing in the bore of the housing, the end with the knife-like edge projections of the least height are inserted first and upon continued telescopic movement of the assembly into the bore of the housing, the sections with the progressively greater projection heights follow in the same line and in the groove already formed by the previous section. By this arrangement each section penetrates and cuts away an additional amount of material and penetrates deeper into the bore surface of the housing. In this manner, it is possible to obtain substantially equal preloading or uniform load pretension or preloading or uniform load distribution over the entire length of the bearing race plate. Additionally as the result of the stepped configuration, a major portion of the knife-like projections penetrate deeper into the bore surface to provide greater torque transmitting capability of the entire assembly.
In accordance with still another feature of the present invention, the knife-like projections instead of being oriented in a straight longitudinal line on the outer periphery of the bearing race plate, may be arranged in a random pattern comprising distributed points or short sections of knife-like projections and each point or section when pressed into the bore of the housing individually penetrates into a still untouched section of the bore surface. This arrangement tends to balance the preloading or tension more uniformly over the entire length of the bearing race plate.